Dr. John Garric on the Quantity of Heat, Se. 39 
the vast.west, for such cliffs are due to the action of winds and 
waves, always in operation on bodies of water. But under-sur- 
__. face currents are not universal, or in such general operation as to 
_ form “everywhere, bars and longitudinal banks or spits. he 
Atlantic Ocean should suddenly settle one hundred feet, or any 
other distance, would there not remain a distinct shore, well de- 
fined and traceable its entire length? At the mouth of some 
rivers and bays or inlets, would be seen limited sand ridges, their 
ses upon an exact level. On the ancient bed of the sea oppo- 
site sandy coasts, like North Carolina and New Jersey, would a 
‘pear long, narrow and rudely parallel ridges, of such materials as 
are easily moved by currents, that would mot be level longi- 
tudinally. 
The evidence of the existence of ancient currents acting upon 
the drift, regularly and irregularly, is abundant. They have act- 
ed at all elevations, as well on the highest lands in Ohio at 135 
feet above the tide, as at the sources of the Mississippi, 1680 feet. 
The evidence is that they were powerful, and in general erratic 
or irregular and fitful. Such currents would not leave ridges, but 
rounded elevations. For this discussion it is immaterial whether 
It is to this wide-spread power that we must resort, to explain 
Most of the diluvial phenomena which are observed. What can 
be reasonably assigned to the wearing action of waves along a 
Coast line, is limited and not pervading; not an universal, but a 
local, tardy and inefficient geological agent. 
_ Arr. VL—On the Quantity of Heat evolved from Atmospheric 
Air by Mechanical Compression ; by Joun Garric, M.D. 
with a few apparent exceptions, an invariable source of heat. 
Atmospheric air, subjected to mechanical compression, evolves it 
Hantities of heat furnished by given volumes, under given pres- 
sures, have b ined. I indeed 
bei s hever been accurately ascertamed. it may, In eed, 
aid that there is scarcely a subject in the whole range of nateue 
_ philoso vy, which has elicited more discordant results. e 
Well €ry phenomenon of nature possesses in itself an interest 
ei calculated to excite the mind to an investigation of its cause. 
